Re: [PATCH RFC v3 04/35] mm: page_alloc: Partially revert "mm: page_alloc: remove stale CMA guard code"

[Alexandru Elisei]

Hi,

On Mon, Jan 29, 2024 at 02:31:23PM +0530, Anshuman Khandual wrote:
> 
> 
> On 1/25/24 22:12, Alexandru Elisei wrote:
> > The patch f945116e4e19 ("mm: page_alloc: remove stale CMA guard code")
> > removed the CMA filter when allocating from the MIGRATE_MOVABLE pcp list
> > because CMA is always allowed when __GFP_MOVABLE is set.
> > 
> > With the introduction of the arch_alloc_cma() function, the above is not
> > true anymore, so bring back the filter.
> 
> This makes sense as arch_alloc_cma() now might prevent ALLOC_CMA being
> assigned to alloc_flags in gfp_to_alloc_flags_cma().

Can I add your Reviewed-by tag then?

Thanks,
Alex

> 
> > 
> > This is a partially revert because the stale comment remains removed.
> > 
> > Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
> > ---
> >  mm/page_alloc.c | 15 +++++++++++----
> >  1 file changed, 11 insertions(+), 4 deletions(-)
> > 
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index a96d47a6393e..0fa34bcfb1af 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -2897,10 +2897,17 @@ struct page *rmqueue(struct zone *preferred_zone,
> >  	WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));
> >  
> >  	if (likely(pcp_allowed_order(order))) {
> > -		page = rmqueue_pcplist(preferred_zone, zone, order,
> > -				       migratetype, alloc_flags);
> > -		if (likely(page))
> > -			goto out;
> > +		/*
> > +		 * MIGRATE_MOVABLE pcplist could have the pages on CMA area and
> > +		 * we need to skip it when CMA area isn't allowed.
> > +		 */
> > +		if (!IS_ENABLED(CONFIG_CMA) || alloc_flags & ALLOC_CMA ||
> > +				migratetype != MIGRATE_MOVABLE) {
> > +			page = rmqueue_pcplist(preferred_zone, zone, order,
> > +					migratetype, alloc_flags);
> > +			if (likely(page))
> > +				goto out;
> > +		}
> >  	}
> >  
> >  	page = rmqueue_buddy(preferred_zone, zone, order, alloc_flags,